Follows Cayman’s lead to combat dengue fever threat
A method of releasing genetically modified Aedes Aegypti mosquitoes into the environment to combat the possible spread of dengue fever in the Cayman Islands by the Mosquito Research and Control Unit – hailed as the first of its kind in the world – has been adopted in Malaysia.
At least 6,000 genetically modified Aedes Aegypti mosquitoes were released into a forest in the Asian country in efforts to curb the spread of dengue fever, according to the Associated Press.
The technique to modify the mosquitoes is done by making the male sterile, and as a result, when it breeds with the female no offspring are produced; thus the population is reduced.
At the time of Cayman’s release of the mosquitoes, Bill Petrie, director of MRCU, said the initiative was essentially a new spin on an old technique, only in this scenario, sterility in the males was achieved by altering their genes, as opposed to being chemically induced by radiation.
The technique, which garnered the interest of the international press, was met with mixed views overseas, though many of Cayman’s residents were satisfied with the methodology, according to results of an online poll, conducted at caycompass.com.
The trial in Malaysia involves placing 6,000 wild, natural males, in addition to the genetically modified mosquitoes that have been introduced, in the same area for scientific comparison.
According to Malaysia’s government-run Institute for Medical Research, no more mosquitoes will be released until the results of the experiment are analysed.
Fighting dengue fever
A leading scholar and professor specialising in infectious diseases at Singapore’s Duke-NUS Graduate Medical School, Duane Gubler, has said that the plan will likely be a success in fighting the spread of dengue fever, if it is combined with other biological control methods.
“We need new tools. Nothing we’ve done in the past 40 years has had an impact” on dengue fever, Gubler told the Associated Press. He is not directly involved with the mosquito release.
Opponents of the new measure contend that getting rid of the mosquito could affect the food chain and throw the ecosystem off balance, in addition to many other adverse effects.
“Humans have had a disastrous record of introducing anything into the environment. This can be classed as interference and the exercise may cause additional problems worse that the one that is trying to be dealt with,” said Campaign Director for GM Freeze, a British nonprofit organisation that opposes genetic modification.
However, Mr. Petrie said, “The Aedes Aegypti mosquito, which is the only mosquito that carries dengue in the Cayman Islands of the 35 species that live here, is actually an invasive species.
It has come along many times and each time we have gotten rid of it. But after Hurricane Ivan, their numbers exploded. That mosquito does not belong here, so there is no moral or ethical dilemma in getting rid of it.”
Mr. Petrie added, “No one is upset about getting rid of roaches or rats or the bacteria that causes cholera, but they also play a role in the ecosystem.”
MRCU Senior Research Officer Angela Harris lauded the experiment as a great success, calling the results brilliant. She said there has been about an 80 per cent reduction of the mosquito in test areas.
“This is a self-limiting technology simply because there is no next generation, and so there is nothing bad to pass on. There should be absolutely no fear about this method.”
She added that it was exciting to see trials being done elsewhere and would be interesting to see what the results are.
As part of the undertaking in the Cayman Islands, MRCU, along with Oxitec of Oxford University, ran the trial here over a six month period, using small isolated areas in East End. This was done in three blocks; one block was where the method was introduced, nothing was done in another block and the third block was used to monitor the population of the Aedes Aegypti mosquito.
Dengue fever is common in Asia and Latin America. Symptoms of the illness include high fever, joint pains and nausea. In severe cases, it can lead to internal bleeding, circulatory shutdown and death. There is no known cure or vaccine.